• Journal of Power Electronics
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• 제18권4호
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• pp.965-974
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• 2018

A new zero-voltage-switching (ZVS) push-pull pulse-width modulation (PWM) converter is proposed in this paper. The wide ZVS condition for all of the switches is obtained by utilizing the energy stored in the output inductor and magnetizing inductance. As a result, the switching losses can be dramatically reduced. A simple auxiliary circuit including two small diodes and one capacitor is added at the secondary side of a high frequency (HF) transformer to reset the primary current during the circulating stage and to clamp the voltage spike across the rectifier diodes, which enables the use of low-voltage and low-cost diodes to reduce the conducting and reverse recovery losses. In addition, there are no active devices or resistors in the auxiliary circuit, which can be realized easily. A detailed steady operation analysis, characteristics, design considerations, experimental results and a loss breakdown are presented for the proposed converter. A 500 W prototype has been constructed to verify the effectiveness of the proposed concept.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.623-628
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• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.321-324
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• 2008

Recently, there is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Among them, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.220-220
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• 2009

We are developing of the evaluation technique and system for testing the performance of circuit breaker using Simplified Synthetic circuit. This facility specification is up to 90[kApeak] and up to 300[kVpeak]. It is possible to verify the interrupting capability by using low-energy and reduce the development period and the cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2169-2171
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• 1998

In order to improved the three phase GTO CSI of high efficiency IM drive with low loss commutation and snubber energy, we studied the energy recovery circuit to recover stored energy in clamping capacitor, dc link inductor and snubber capacitor, used an induction motor as the load of inverter. Specially, we investigated how dc input power is increased or decreased according to size of dc link inductor. The validity of this system is proved through experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.160-163
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• 2004

A passive lossless turn-on/turn-off snubber network is proposed for the boost PWM converter. Previous AC/DC PFC Boost Converter perceives feed forward signal of output for average current-mode control. Previous Boost Convertor, the Quantity of input current will be decreased by the decrease of output current in light load, and also Power factor comes to be decreased. Also the efficiency of converter will be decreased by the decrease of power factor. The proposed converter presents the good PFC, low line current harmonic distortions and tight output voltage regulations using energy recovery circuit. All of the semiconductor devices in the converter are turned on under exact or near zero voltage switching(ZVS). No additional voltage and current stresses on the main switch and main diode occur. To show the superiority of this converter is verified through the experiment with a 640W, 100kHz prototype converter.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.685-688
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• 2005

플라즈마 디스플레이를 위한 효율적인 서스테인 드라이버와 이를 리셋 회로와 결합시키는 유용한 결합 방법을 제시한다. 제안된 서스테인 드라이버는 외부 인덕터와 패널에 존재하는 기생 커페시터 간의 직렬공진 방식을 이용한다. 이 회로는 4개의 스위칭 소자, 인덕터, 전원공급을 목적으로 하는 외부 커패시터로 구성된다. 기존의 방식과 비교하여 입력전원전압이 두배가 되지만 스위칭 소자에 가해지는 전압스트레스는 기존의 값과 거의 동일하며, 입력 전압을 별도의 승압없이 리셋 회로의 전원으로 사용할 수 있는 장점을 가진다. 이러한 회로적 구조는 서스테인 드라이버와 리셋회로를 간단히 구성할 수 있다. 이론적 분석을 바탕으로 동작원리와 설계 예를 제시하며, 7.5인치 AC PDP 패널을 이용한 실험을 통해 타당성을 검증한다.

• KEPCO Journal on Electric Power and Energy
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• 제6권4호
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• pp.393-397
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• 2020

무효전력 보상설비인 분로리액터는 전력계통의 부하 패턴에 따라서 하루에도 수 회 정도 차단기에 의해 운전되거나 정지된다. 분로리액터개폐 시 몇 가지 요인에 의해 발생하는 과전압은 차단기의 절연 성능을 저하시키며, 계통을 구성하는 전력기기에 심각한 전압 스트레스를 유발한다. 분로리액터 개폐 과정에서 발생하는 과도현상을 측정하는 것은 계통을 모의하여 차단기 성능을 검증하는 시험소 수준에서는 가능하나, 실제 계통 운전 중에 발생하는 과도현상을 측정하는 것은 여러 가지 제약으로 어려움이 있다. 따라서 본 논문에서는 실 계통에서 지상 소전류 차단과정에서 가혹한 과도회복전압(TRV: Transient Recovery Voltage)을 유발하는 재발호(reignition)나 전류재단(current chopping) 현상에 대한 해석을 위해 전자계과도해석프로그램(EMTP: Electro-magnetic Transients Program)을 활용한 모델링 과정과 이를 토대로 분로리액터 개폐 과정에서 차단기의 고장을 유발하는 주된 현상에 대해 해석하고자 한다.

• 한국태양에너지학회 논문집
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• 제23권3호
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• pp.29-35
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• 2003

Generator for wind power can be either synchronous or asynchronous (induction) types. Induction and synchronous generators behave in a different way when subjected to severe faults. Induction generators does not have an angle stability limit and short circuit in the neighborhood of an Induction generator causes the demagnetization of the machine when the fault is cleared, the voltage raises slowly, while the grid contributes with reactive power to the generator and the magnetic flux recovers. On the other hand in the synchronous generators the recovery of the voltage is immediate, since the excitation of the rotor angle comes from an independent circuit. This paper shows the result of the transient state analysis in the network connected to wind generation system Several case studies have been conducted to determine the effect of the clearing time of a fault on the network stability. It has been found that the critical clearing time can be as low as 61ms in the case of induction generator compared to 370ms in the case of synchronous generator.

• Journal of Power Electronics
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• 제17권3호
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• pp.579-589
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• 2017

In this study a new high step-up dc-dc converter is presented. The operation of the proposed converter is based on the capacitor switching and coupled inductor with a single active power switch in its structure. A passive voltage clamp circuit with two capacitors and two diodes is used in the proposed converter for elevating the converter's voltage gain with the recovered energy of the leakage inductor, and for lowering the voltage stress on the power switch. A switch with a low $R_{DS}$ (on) can be adopted to reduce conduction losses. In the generalized mode of the proposed converter, to reach a desired voltage gain, capacitor stages with parallel charge and series discharge techniques are extended from both sides of secondary side of the coupled inductor. The proposed converter has the ability to alleviate the reverse recovery problem of diodes with circuit parameters. The operating principle and steady-states analyses are discussed in detail. A 40W prototype of the proposed converter is implemented in the laboratory to verify its operation.